Fig. 1.

Simplified representation of main characteristic symptoms in PCH and similar conditions. DSD = Disorder of Sex Development, CC = Corpus callosum, MEB = Muscle-eye-brain disease, WWS = Walker Warburg syndrome, CDG1A = Congenital disorder of Glycosylation type Ia, SCA = Spinocerebellar ataxia. Note that exceptions are possible in most categories due to large phenotypic variability. *The strongest correlation of a dragonfly configuration of the cerebellum and dystonia is with PCH2A. In other PCH2 subtypes, that are all very rare, cerebellar hypoplasia may be less profound and extrapyramidal movement disorders absent. In PCH2E, brain MRI is initially normal; cerebellar atrophy becomes apparent in the first year of life. In addition, osteoporosis and scoliosis were reported in PCH2E.** (Relative) sparing of the pons can also be seen in milder affected patients with other PCH subtypes